Clinical psychologists and neuropsychologists are traditionally taught
that cognition is mediated by the cortex and that subcortical brain
regions mediate the coordination of movement. However, this argument can
easily be challenged based upon the anatomic organization of the brain.
The relationship between the prefrontal cortex/frontal lobes and basal
ganglia is characterized by loops from these anterior brain regions to
the striatum, the globus pallidus, and the thalamus, and then back to
the frontal cortex. There is also a cerebrocerebellar system defined by
projections from the cerebral cortex to the pontine nuclei, to the
cerebellar cortex and deep cerebellar nuclei, to the red nucleus and
then back to thalamus and cerebral cortex, including all regions of the
frontal lobes. Therefore, both the cortical-striatal and
cortical-cerebellar projections are anatomically defined as re-entrant
systems that are obviously in a position to influence not only motor
behavior, but also cognition and affect. This represents overwhelming
evidence based upon neuroanatomy alone that subcortical regions play a
role in cognition. The first half of this book defines the functional
neuroanatomy of cortical-subcortical circuitries and establishes that
since structure is related to function, what the basal ganglia and
cerebellum do for movement they also do for cognition and emotion.
The second half of the book examines neuropsychological assessment.
Patients with lesions restricted to the cerebellum and/or basal ganglia
have been described as exhibiting a variety of cognitive deficits on
neuropsychological tests. Numerous investigations have demonstrated that
higher-level cognitive functions such as attention, executive
functioning, language, visuospatial processing, and learning and memory
are affected by subcortical pathologies. There is also considerable
evidence that the basal ganglia and cerebellum play a critical role in
the regulation of affect and emotion. These brain regions are an
integral part of the brain's executive system. The ability to apply new
methodologies clinically is essential in the evaluation of disorders
with subcortical pathology, including various developmental disorders
(broadly defined to include learning disorders and certain psychiatric
conditions), for the purpose of gaining greater understanding of these
conditions and developing appropriate methodologies for treatment.
The book is organized around three sources of evidence:
- neuroanatomical connections;
- patients with various disease processes;
- experimental studies, including various imaging techniques.
These three sources of data present compelling evidence that the basal
ganglia and cerebellum are involved in cognition, affect, and emotion.
The question is no longer if these subcortical regions are involved in
these processes, but instead, how they are involved. The book is also
organized around two basic concepts: (1) the functional neuroanatomy of
the basal ganglia and the cerebellum; and (2) how this relates to
behavior and neuropsychological testing.
Cognitive neuroscience is entering a new era as we recognize the roles
of subcortical structures in the modulation of cognition. The fields of
neuropsychology, cognitive psychology, neuropsychiatry, and neurology
are all developing in the direction of understanding the roles of
subcortical structures in behavior. This book is informative while
defining the need and direction for new paradigms and methodologies for
neuropsychological assessment.
